Major field crops, especially cereals, produce large
quantities of stem and leaf in addition to their saleable product, which is
usually seed. The straw or stover is usually over half the harvestable
vegetation of the crop. Such coarse roughages cannot be eaten by humans, but
they can be transformed into economic products by livestock. Some cereals and
pulse crops are also grown specifically for hay, and details of their
cultivation as forage are given in Chapters III to VI.

Our subject here is the residues of field crops that are grown
for purposes other than fodder. While these residues are coarse roughages, they
are often no worse than, and possibly better than, dried, mature, tropical
grasses. This should be kept in mind when dealing with small-scale agriculture
in tropical systems: better straw harvesting and storage, with possibly urea
treatment, may be cheaper and more productive than going to great trouble to
harvest bush hay. Details of the feeding value of some residues are given later,
in Chapter X.

Straw is the stems and leaves of small cereals; chaff is husks
and glumes of seed removed during threshing (chaff is usually a richer feed than
straw, but more difficult to feed because of awns, etc.). Modern
combine-harvesters generally deliver straw and chaff together; other threshing
equipment separates them. Stover is the field residues of large cereals, such as
maize and sorghum. The leaves and stems of pulses are variously described as
haulms or vines. Stubble is the stumps of the reaped crop, left in the field
after harvest. Agro-industrial wastes are by-products of the primary processing
of crops, including brans, milling offal, dal polishings, press-cakes and
molasses. These are mostly concentrate or near concentrate feeds, but since they
depend on processing rather than crop production, they are beyond the scope of
this book. Brans from on-farm husking of cereals and pulses are fed to livestock
or foraged directly by backyard fowls.

Straws and stovers have always been an important part of
agriculture. Until the advent of cheap inorganic fertilizers and mechanization,
they were an integral part of large-scale farming as feed for draught and other
stock and litter for the production of manure, which was essential to the
maintenance of fertility. At the small-scale farming and subsistence levels,
agricultural residues have retained their importance, indeed, the importance is
growing because of the ever-decreasing access to free grazing as cropping area
expands. With changing production technologies in mechanized agriculture, straws
were for some time thought to be of so little value that they were often burnt
in the field. Environmental legislation, and the development of straw treatment
to improve digestibility, has brought an end to straw burning in most developed
countries, where it is now either fed to livestock or used for industrial
purposes.

The change of land use from grazing to cereal production does
not usually reduce the amount of roughage available for livestock, as the amount
of straw and stover will be as great or more than the natural herbage previously
on offer. In the vast irrigated lands which have been developed in arid and
semi-arid areas (e.g., Asia, Egypt, Sudan) the amount of roughage from crops is
vastly greater than the former production from natural grassland. Rice-based
production systems yield large amounts of straw. Frequently, the change from
extensive grazing to arable or mixed farming leads to an increase in the number
of livestock kept. Many agricultural production systems are mixed, with both
cropping and livestock, often multipurpose; with decreasing grazing
availability, the stock rely on crop residues as the basis for their nutrition.
It is essential, therefore, that these residues be used to their best advantage
and are stored correctly so that the livestock have an adequate supply
throughout the year. Since crop residues in themselves do not constitute an
adequate ration for production or for young stock, complementation by high
quality green fodder, and sometimes concentrates, must usually be
foreseen.

The ease of harvesting and drying residues depends, of course,
on the climate. In sub-humid and drier climates and in temperate regions there
are usually few problems with straw harvesting. In the humid tropics and
subtropics, however, the weather at harvest time may be such that it is
difficult, if not impossible, to conserve straw, and especially legume haulms,
in good condition. Groundnut tops harvested under hot dry conditions, for
example, are an excellent feed, but where the harvest is under moister
conditions the tops usually become a blackened, diseased mass before they can be
dried. The proper drying of rice straw during the rainy season and on wet land
is difficult, if not impossible, especially when there are many other demands on
labour.

Stubbles are frequently grazed once the crop is removed, They
often contain, in addition to the bases of the cereals and some straw, valuable
feed in the form of grain which has been lost in the harvesting process,
especially after mechanical harvesting, and weeds. Some methods of grain
harvesting leave the plant standing after the heads or cobs have been removed by
hand; this is common with small-scale farm systems for rice, maize, bulrush
millet, finger millet and sorghum. Where feed is plentiful or where labour is
scarce, these residues may be grazed in situ. This is advantageous for
the livestock at the time, in that it allows them to graze selectively and
probably find at least a maintenance diet from what might be a sub-maintenance
feed if taken as a whole. It does, however, lead to a lot of wastage through
trampling. Where there is an overall shortage of roughage for the dry season or
winter it is preferable to harvest, dry and store as much of the crop residues
as are necessary to assure the farm's roughage needs through the lean
season.

Traditional ways of organizing grazing of crop residues may
develop where specialized agricultural and stock-rearing communities are in the
same area, such as the interaction of the Fulani herds in West Africa with
several settled agricultural groups. Stubble grazing rights may be given to the
herders (with or without payment) to the mutual benefit of both communities: the
livestock eat the stover and also recycle fertility to the arable land; the
herds are often kraaled on specified fields at night to build up their
fertility. Recently, especially in drought periods, however, there has been a
move towards harvesting the stover and selling it to passing herds.

In North Africa, transhumant flock-masters (who graze their
herds from the desert fringe to the more northerly agricultural lands, according
to season) buy stubble and fallow grazing in the crop-producing, higher rainfall
areas to feed their herds through spring and summer. The shepherds are skilled
in estimating the amount of grazeable forage on any given piece of land and in
finding a succession of fields to see them through the season.

Crop residues in soil conservation

The great role of stubble in protecting soil against both
hydraulic and aeolian erosion is well known. Stubble-mulching allied to minimum
tillage is a well-established technique for protecting soil and conserving
moisture in large-scale farming in cold semi-arid regions. Stover left on the
field will also protect the soil, and cutting crops like maize and sorghum well
above soil level can provide useful protection to the soil. In small-scale farm
systems, however, straw and stover are often so greatly sought after as feed,
thatch, bedding and fuel that crops are frequently cut to ground level, and
maize roots may be dug out and dried as fuel.

Competing uses

Straws, stovers and chaff have many uses other than as animal
feed within the farm economy, and these must be taken into account when
assessing availability and profitability in livestock feeding systems. Within
livestock production systems, straw is also used as litter and bedding
(providing farmyard manure or compost), and chopped wheat straw is locally much
in demand as poultry litter. Straw, especially rice straw, is often purchased by
paper factories; straw is also widely sold for use as packing materials; straw
and rice husk is widely used in semi-artisanal brick manufacture; chopped straw
mixed with mud is used for plastering, both internally and (in hot, dry
climates) externally; the strong stems of maize, sorghum and bulrush millet are
used in traditional building, screens and grain stores; long straw is used as
thatch; and straws and stovers are used as fuel in areas of scarcity, alone or
chopped and mixed into dung cakes.

Straw

The proportion of straw, or stover, to grain varies from crop
to crop and according to yield level (very low grain yields have a higher
proportion of straw - the ratio is infinite when a crop fails through drought)
but is usually slightly over half the harvestable biomass. The height of cutting
will also affect how much stubble is left in the field: many combine-harvested
crops are cut high; crops on small-scale farms where straw is scarce may be cut
at ground level by sickle or uprooted by hand, as is common on the Loess
Plateau.

Rice straw

This is one of the most important cereals in the world, and
especially so in Asia. Much is grown under small-scale farm conditions, with the
straw widely used as a feed for work and milch stock. Methods of harvest vary.
Often, in small-scale farm systems, either the heads or the whole crop is cut by
sickle; frequently the crop will be cut while still in standing water because of
the weather or lack of water control. The grain is then threshed out by beating
on a rack or stone, or by using a small thresher. Mechanized rice production is
usual in areas where combine-harvesters can be used. Rice straw is unusual in
that the stem is more digestible than the leaves, the opposite of other cereals.
For livestock feeding, it is therefore advantageous to cut it as close to the
ground as possible. With hand harvesting, the crop is often cut when the straw
is still relatively green. This will produce a higher quality straw for feeding
than from mature plants. When only the heads are harvested the straw should be
cut as soon as possible after the heads are removed (if labour is available),
and dried to conserve its quality as a feed.

Drying rice straw is often a problem in high-rainfall areas
because double-cropping means that at least one harvest is under very wet
conditions. With the pressure of work at threshing time, it is difficult to
ensure adequate care in spreading out the threshed straw to dry, and so a poor,
mouldy product is often the result. Wherever possible, rice straw should be
dried (on bunds and dry areas) as soon as possible after threshing in order to
ensure the best possible straw for livestock feed. In high rainfall and flooded
areas, such as parts of Bangladesh, straw drying is almost impossible during the
rainy season. Where drying is very difficult, the feasibility of using urea or
ammonia treatment as a preservative, as well as a means of improving
digestibility and intake, should be studied.

Rice straw is regularly fed to ruminants throughout the
rice-growing countries. It is often the main food of mature draught stock
(cattle and buffaloes) over most of the year and they seem to work and survive
on it despite its low digestibility and protein content. It is often fed ad
libitum and sometimes grazed. This gives the animals the opportunity for
some selection of the parts they consume. In those rice-growing countries where
milk is traditionally consumed, rice straw is also fed to dairy cattle, and more
especially buffaloes, but with supplements of green fodder and concentrates.
Rice straw and husks have many uses other than animal feed and are traditionally
used in brick-kilns, as packing material, and for paper-making.

White straws

The straws of the common temperate cerealshave long
been fed to livestock and are still very important in developing countries.
Developments in harvesting methods may have affected straw quality in some parts
of the world, and in the temperate zone especially. The traditional method was
to mow the crop before it was in danger of shattering, then bind it into sheaves
(originally cut by scythe or sickle and hand-bound; later mechanized by the
reaper-binder), where the ripening and drying of the grain was completed before
threshing, which might take place much later, with the crop stored in stacks in
the interim. More modern methods, and especially the introduction of combine
harvesters and grain drying, usually mean that the crop is cut at a slightly
more mature stage than was the case previously, with more leaf loss and straw of
lower feeding value. Modern clean-weeding by herbicides has greatly reduced the
grasses and other edible herbage which, formerly, was mixed with the lower part
of the straw.

Farmers' opinions differ greatly, from country to country, as
to the feeding value of wheat straw. In western Europe it is considered very
poor, and not fed except in emergency (oat and barley straw were the only ones
recommended as feed in UK until modern straw-treatment techniques were
introduced), but now it is used after ammonia treatment. In the traditional
wheat-growing countries of Asia and North Africa, however, wheat straw is highly
prized and great care is taken in collecting and storing it. The form of straw
depends on the threshing method. Where threshing was by flail, long straw is
produced, and modern threshers give the same result. Where threshing was through
treading by animals or with a ridged roller, the straw is broken into pieces 5 -
10 cm long (tibn, bhusa) and this system was very widespread in
North Africa and Asia. Treading has now often been replaced by threshers; those
used in India and Pakistan are constructed to chaff the straw during threshing.
Chaffed straw is often stored in tightly-packed stacks, mud-plastered to protect
them from rain and livestock. Mud covering can also be used to seal stacks for
urea treatment.

Oat straw is a good and palatable roughage, as is barley.
These straws are easily collected, handled and baled in mechanized systems with
ordinary haymaking equipment.

The straw of foxtail millet (Setaria italica), which is
an important crop in northwestern China, is well accepted by livestock. Finger
millet (Eleusine coracana) straw is considered a good feed in India and
Nepal; the heads ripen unevenly and are hand-harvested in stages; the straw is
cut and dried thereafter. The straw of common millet (Panicum miliaceum)
is hairy and its palatability mediocre.

Stover

The residues of maize, sorghum and millets are major forages
in developing countries, and maize stover is also widely used in commercial
agriculture. In small-scale farm systems, stover is usually handled and dried in
the long, unchopped state, often by stooking in, or on the boundary of, the
field prior to storage. In large-scale systems it may be baled, but can also be
collected by forage-harvester and ensiled with or without urea
treatment.

Maize Stover

Maize is the best of the cereal stovers for livestock feed.
Where very abundant in relation to the livestock, it can be grazed off;
otherwise, on large enterprises, it can be ensiled or collected and dried. Many
small-scale farm systems collect the stover when the cobs have been harvested
and either dry it in the field or at the homestead. In some places of fuel
scarcity, even the roots are dug up together with the stem bases and used as
fuel. Cut stover can be ensiled if chopped, moistened, well compacted and
sealed.

Maize stover has a higher nutrient content than most straws,
with about 6% CP. In North America, it is frequently fed to dry, pregnant cattle
as basis of their ration; either grazed or chopped, and fed with or without
being ensiled. It is often stored by stacking or baling after field
drying.

Sweet-corn cobs, now a widely-grown commercial vegetable for
fresh use, canning and freezing, are harvested while the plant is still green,
and thus provide a large yield of high-quality roughage as a by-product.
Sweet-corn stover benefits from being left growing a few days after harvest of
the cobs. Maize is often harvested as roasting cobs, for sale in urban areas; as
it is at a more mature stage than sweet-corn, the stover from such plants is a
superior feed (or if dried, hay) compared to that from a fully-mature
crop.

This is a valued feed, especially if cut and dried immediately
after the heads have been harvested for grain. Frequently, the heads are
hand-harvested as they ripen and the stover harvested separately, preferably by
cutting as green as possible after seed harvest and field drying in the same way
as sorghum hay. Grazing in situ is done in some countries, but it is
potentially dangerous because of the likelihood of cyanogenic substances in any
re-growth, and also wasteful, as is always the case with grazing of stover. The
stems of tall, robust varieties are used for fencing, building grain cribs and
other light construction work.

Bulrush millet

A coarse, poor feed, usually reputed to be of low
palatability; it is nevertheless popular in parts of India. Under small-scale
farm conditions, the heads are hand-harvested and the stover cut once grain
harvest is complete.

Residues of pulse crops

Many of these have a higher feeding value than cereal straws,
but are much more difficult to recover; in humid climates the leaves tend to
discolour or drop at or before harvest, and in dry conditions they shatter.
Where the final drying of the crop takes place at the homestead, it is easier to
recover the leaves and stems. The leaves and stems of other commonly grown
pulses, but not described below, are many of them also useful feeds, such as the
various Phaseolus spp., green and black grams, and the leafy parts of
pigeonpea. Fava beans, however, have coarse, woody stems, while the straw of
chick-pea (Cicer arietinum) has a very high oxalic acid content, is
unpalatable, and reputed to be toxic.

Groundnut tops as "hay"

In areas where good drying weather occurs at harvest time,
very useful hay can be produced from groundnut haulm. Groundnuts should be dug
when the leaves begin to change colour to a yellowish shade and the haulms begin
to dry. Sever the tap root and dig up the nuts then windrow and dry the foliage.
The partly dried haulms may be stacked in small heaps. In the drier parts of
Asia, groundnut tops are carefully harvested and then dried at the homestead, on
house roofs and other sunny places protected from livestock. They may also be
stacked on stakes, dried for 3 to 6 weeks and then threshed: the straw from this
method is useful, despite its appearance.

Pea haulms

Green vines from canning, fresh and freezing crops are a
valuable by-product and are best conserved as silage. The frozen pea crop is a
large one, mainly grown in developed countries. Pease straw, from fully mature
plants for dried pea production, is a useful roughage.

Soybean haulms

The haulms from hand harvested crops when properly cured are a
useful feed. Successful harvesting is, however, very dependent on suitable
weather and often the leaves are diseased or senescent by harvest
time.

Cowpea haulms

These are an excellent fodder and are carefully stored in
countries where the climate at harvest time is suited to drying. They are
traditionally used in sheep-fattening in the Sahelian zone.

Traditional storage and utilization
systems

Storage systems have evolved with the many crops and livestock
production systems associated with crop residues. Often they are similar to
those used for hay and described in Chapter III. The methods of storing white
straws depends on the threshing system (i.e., whether long straw or chaffed).
Long straw is often stacked and thatched, or small quantities are stored on
house-roofs, in lofts and outbuildings. Tree storage is also used, to keep it
above the reach of livestock. Stacking should be on dry foundations of stone or
brushwood. Chaffed straw is mainly produced in semi-arid areas; tightly packed
stacks or heaps protected with mud plaster are a common system for storing large
quantities. These may be in a corner of the field, on waste land or near the
eventual point of use. In dry areas, such stacks are made directly on the
soil.

Rice straw is always long (and almost impossible to chaff).
The care taken in its storage and conservation varies greatly from place to
place. Usually it is roughly heaped, either on field edges or where livestock
are kept or gathered at night. Often, the stock are allowed direct access to the
stack and eat selectively. It should preferably be fed in addition to other
feed. Where there is an overall scarcity of roughage, however, rice straw is
stored with more care and may be put in the crotches of trees, or in stacks
protected from stock. Cattle shelters with the straw stacked on the flat roof
are used in some areas.

Stovers are still grazed in some countries, especially in
parts of Africa; this is wasteful but does save a lot on labour and returns some
dung to the fields. Where dried roughage is highly valued and there is a dry
season after harvest, stovers are usually dried in sheaves, and in dry areas are
often stored by stacking the sheaves together with the stems more or less
vertical.

Better harvesting and
storing

Production of more and better conserved straw for livestock
feed could be attained in several ways. Dual-purpose varieties of cereals -
where straw quantity and quality are taken into account in addition to simple
grain yield- are one approach, but their extension will depend very much on the
economics of straw and livestock vis à vis grain, as well as the
grain quality of such varieties when grown for subsistence. The general trend in
cereal variety development has been towards shorter growing cultivars with less
straw; the "stay green" quality of some maize cultivars, however, not only helps
increase their grain yield but also provides a better stover for animal
feed.

Improvements can be made to straw yield (or recovery) and
quality, without changing cultivars, by attention to agronomic details at the
time of harvest and immediately afterwards. Where the whole crop is cut at
harvest, the straw should be dried as quickly and thoroughly as possible, and
stored with care. Where heads or cobs are hand-gathered, the cutting and drying
of the stover or straw should be done immediately grain harvest is completed,
with the fields protected from grazing livestock in the period between grain
harvest and straw collection. Stooking of maize and sorghum allows final
ripening of the grain after the plant is cut; this provides stover of better
feeding value than if the crop is allowed to mature standing. Topps and Oliver
(1993) give some analyses from Zimbabwe (Table 7). As with hay, careful carting
and storage (with or without baling) are very important.

Table 7. Effect of stooking maize on stover
composition

Stage of cutting

TDN (%)

Protein (%)

Digestible protein (%)

Stooked

45

4.0

1.0

Late-cut

40

3.0

2.0

Field handling and baling

Themechanizedhandling of the straw of small
cereals is similar to that of hay, as described in Chapter II. Since straw is
from the mature and relatively dry plant, and much less leafy, it is much easier
to cure than green herbage. Windrowing followed by pick-up baling can often be
done soon after the combine-harvester has passed. Straw to be transported off
the farm is often made into high-density bales - over 200
kg/m3.

In small-scale farm systems, the crop is usually taken to a
central point for threshing (which may or may not be on the field). The straw
will therefore have to be taken from the threshing area for final drying, if not
already dry enough (especially likely in the case of rice). With some crops and
harvesting systems, most of the straw may be left in the field after the heads
are harvested; e.g., rice in some systems, and finger millet: such straw should
be harvested and dried as quickly as circumstances allow. Small-scale farms
usually store straw un-baled, long or chaffed according to the crop and
threshing system.

Straw treatment

Straw treatment improves both quality and conservation. When
straw is treated with an alkali, the ester linkages between lignin and the
cell-wall cellulose, polysaccharides and hemicelluloses are hydrolysed, thus
causing the carbohydrates to become more available to the micro-organisms in the
rumen. Sodium hydroxide was used but has problems of cost and handling.
Anhydrous ammonia or a solution of ammonia in water is now used. Gaseous ammonia
is best suited to large operations and can only be used where the distribution
system for ammonia (tankers, cylinders) is available. It has the great advantage
that the straw can be treated in the bale when baled material is being treated.
Ammonia acts as a fungicide (the process also creates anaerobic conditions)
while also increasing crude protein content. Treatment requires airtight
conditions.

For small-scale farms, it is generally more convenient to
generate ammonia from urea, a widely-available fertilizer which is familiar to
most farmers, by the "wet ensiling process". Ammonia is produced from urea,
which is broken down by the action of urease (NH2-CO-NH2 +
H2O ® 2NH3 + CO2), through bacterial
action, when it is mixed with moist straw; the process is rapid at high
temperatures and so is suited to subtropical and tropical conditions rather than
to temperate climates or subtropical winters.

The following description of straw treatment with urea is from
the FAO (1993) publication Tropical Feeds:

"Of the chemical treatments available, urea
treatment has the most relevance to small farmers. Urea is added to the straw at
the rate of 5% w/w (air-dry basis). The quantity of water may range from 0.3-1
l/kg of air-dry straw, with a minimum being applied in areas with water
scarcity. If the straw is wet with rain or with freshly harvested straw
containing much green material, urea can be applied without prior
dissolution.

"Straw can be kept in various ways during treatment. Airtight
conditions produce the best results. The conventional method is to use plastic
sheet. A concrete silo, above ground and lined with plastic, will invariably
produce good results, but concrete and bricks can be costly and difficult to
obtain in some circumstances. A construction of earth bricks (clay mixed with
straw), as used for making houses or storing rain in parts of Africa, is also
suitable. Oil-drums or plastic bags can be used for very small-scale (single
animal) quantities. Alternatives can be worked out locally: in dry areas, they
can be below-ground pits lined with straw, banana leaves, or bamboo leaves or
mats; in wetter areas, they can be stacks against a wall or fine-mesh wire
(chicken wire) containers. When straw is stacked against firm structures (walls,
pits, meshed wire), trampling can be done to compact the material and wet straw
will not allow air to enter. Even if 100% airtight conditions are not achieved,
good results can still be obtained and the outer (untreated) parts can be fed to
animals with lower requirements, such as draught bullocks or dry cows, while the
inner part is fed to growing and lactating animals.

"Treatment time may vary from 1 - 4 weeks. In intensive work
undertaken in Bangladesh and Sri-Lanka in the early 1980s, 7 - 10 days was
normal, with no benefits in animal performance obtained by longer treatment.
However, temperature and treatment time are inversely correlated and more time
is required in winter or in colder climates. In well-compacted straw, the
temperature rises over 10°C after one week."

Figure 40. Urea-treated
straw being taken from a mud-cased heap. Note the berseem behind (Punjab,
Pakistan)

A detailed description of small-scale farm processing of straw
with urea is given by Dolberg in FAO's Better Farming Series (FAO,
1995c), and gives the differences between treated and untreated straw shown in
Table 8.

Table 8. Expected effect of straw treatments

Untreated straw

Treated Straw

Poor-quality feed

Reasonable-quality feed

Unpalatable, so animals eat little

Palatable, so animals eat more

Animals lose weight

Animals gain weightAnimals produce some milk

The signs of successful treatment are given as:

- The straw has changed colour to dark yellow or
brown.- The straw has a strong ammonia smell.- The straw is softer than
untreated straw.- The animals, after a period of adapting, eat one-third
more than untreated straw.

The equipment needed for simple, small-scale treatment is a
means of weighing straw (usually several standard bundles or baskets would be
weighed and volume measures used thereafter); a volume measure for the standard
quantity of urea used; a ten-litre bucket and a large water reservoir; the
concentration used is 5%, or ½ a kilogram in 5 litres of water for every 10
kg of straw treated. Whereas straws need not be chopped before treatment,
stovers must be, unless they can be very well compacted.

Urea treatment should be timed to fit in with crop-harvesting
operations and wherever possible done before the straw or stover has already
been stored or stacked, to avoid double handling and extra labour. This will
also help ensure that the straw is in good condition; dirty, mouldy or rotten
straw must never be treated as the result would make a poor and potentially
dangerous feed.

Straw in standard and big bales is suitable for ammonia
treatment as the ammonia gas can diffuse through the straw without pre-mixing or
opening of bales. Many farms now use anhydrous ammonia as fertilizer. Some of
the ammonia reacts with the straw to provide some nitrogen available to the
rumen microflora. Anhydrous ammonia or a 35% aqueous solution are used. The
straw must be completely sealed - usually under plastic sheet. Standard bales
are stacked 50 ´ 4 or 5 bales wide, in stacks of about 30 t on a plastic
sheet; the top is slightly ridged to shed water; the whole is covered with
another plastic sheet which is sealed by weighting. The sheet may be roped or
netted as protection against wind. Ammonia is injected through holes in the
sheet, which are immediately sealed with a special seal. Big bales can be
stacked, but care is necessary; they are usually put in plastic sleeves, singly
or in groups, and injected. The site for storing treated big bales must be
carefully chosen to ensure drainage, and access at the time when they are to be
used.

Other field crops

Sugar cane

The tops of sugar cane, the terminal leaves, the bundle sheath
and one or more nodes are a valuable feed. The point of cutting depends on the
millers' requirements, but is usually at the highest fully-formed node.
Quantities vary with cultivar, management practice and growing conditions, but
is of the order of 18% of the aerial biomass and a reasonable crop can,
therefore, provide 5 t/ha of dry matter. Where cane cutting is seasonal,
livestock often depend on cane tops during the winter harvesting season when
other feed is scarce. For example, in the sugar growing areas of the
Indo-Gangetic plain, canes are often a welcome source of roughage at the end of
winter. The tops are readily accepted by livestock, but are low in protein and
require supplementation. Where animals can graze them selectively or if the dry
leaves are removed, their feeding value is improved. Cane tops can be conserved
as silage. Sugar cane can be grown as a fodder and is unusual in grasses in that
it has its highest energy content at maturity. It can be chaffed and fed direct,
or ensiled; cane can also be fractionated using simple crushers, so that the
juice is used for monogastrics and the residue for ruminant feed.

The wastes from processing - bagasse and molasses - are also
useful feed sources, especially the latter, which is high in readily available
energy, but these are agro-industrial by-products. Bagasse is also used as fuel
and in the manufacture of particle-board. The residues of artisanal
cane-crushers has much more sugar left in it than factory bagasse and is a much
more useful feed in consequence.

Sunflower heads

The threshed heads of sunflower, provided that they have been
dried before threshing (this depends on the climate), are a valuable feed. In
the Trans-Nzoia area of Kenya, where sunflower is grown for bird-seed, the crop
is harvested by cutting the stem at waist height with a sloping cut when the
seeds are fully formed, cutting off the seed-head and spiking it, seed-side
down, on the cut stem to dry and avoid bird damage. The heads are further sun
dried before threshing. The threshed heads, which may contain some seed, are
then put through a coarse hammer mill before being added to ruminant feeds. The
crude protein content of the heads is 7 - 9%. Once dried, they can be stored for
long periods. With the tall, grey-striped cultivar in a reasonable crop (2
t/ha), the ratio of seed-head to seed was around 1.2. The stems are poor feed
and are usually either ploughed in or used as fuel. In Zimbabwe, heads are
sometimes dried once the seed has formed and then ground, without threshing, as
feed. Topps and Oliver (1993) give the crude protein content of the resulting
meal as 14% and the crude fibre as 25%.

Cotton sticks

The leaves, twigs and unripe bolls of cotton are eagerly
browsed by small ruminants after harvest and are a good feed, but only if the
insecticide regime of the crop has been a suitable one! Sticks can be dried for
winter feed, with the thicker stems used as fuel.

Miscellaneous moist residues

Not all crop residues suitable for livestock are dry. Many
fresh residues are locally important as feed sources. Sugar beet tops are a good
feed, but are conserved by ensiling, not drying (the pulp - a very valuable feed
- is an agro-industrial by-product). Horticultural crops produce large
quantities of herbage which, while not consumed by humans, is nevertheless
useful animal feed and used opportunistically. The unsaleable parts of brassicas
(and a hectare of cauliflower can yield a lot) are usually only suitable for
feeding fresh. Sweet potato tops are an excellent feed, equivalent to good
legumes. Yam peelings are traditionally fed to backyard sheep and goats in the
yam belt of West Africa. Banana pseudo-stems are useful roughage, widely used as
cattle feed - they are not suitable for drying, but can be ensiled. Some tree
prunings are useful feed, especially for small ruminants, but they are usually
available only sporadically and browsed on the spot, and often the bark is eaten
as well as the leaves (e.g., mulberry poles in the Himalayan region).

Where tree prunings are available on a large scale, the leaves
may be conserved for local use. The olive, which is cultivated on large areas in
the Mediterranean zone of Europe and North Africa, and now also grown
commercially in the Americas, provides large quantities of twigs and leaves at
pruning. These are highly palatable to livestock. It is preferable to feed the
leaves green, but they may be dried for later use or stripped off the branches
and ensiled. Undergrade fruit and some wastes from fruit and vegetable
processing (citrus marc, pineapple waste, pea haulms) are conserved as
silage.